Subaqueous audio-sound transmitter



Jan. 25, 1966 F; M. FREIS 3,231,853

SUBAQUEOUS AUDIO-SOUND TRANSMITTER Filed Dec. 4, 1963 2 Sheets-Sheet 1 FIG! F|G.2

INVENTOR: FREDERlCK M. FREIS ATT'YS Jan. 25, 1966 FREIS 3,231,853

SUBAQUEOUS AUDIO-SOUND TRANSMITTER Filed Dec. 4, 1965 2 Sheets-Sheet 2 INVENTOR. FREDERICK M. FREIS BY walla- ATT'YS United States PatentC 3,231,853 SUBAQUEOUS AUDIO-SOUND TRANSMITTER Frederick M. Freis, 1451 E. 86th St., Chicago, Ill. Filed Dec. 4, 1963, Ser.'-No. 327,919 Claims. (Cl.340 8) This invention relates to the structuring of subaqu'eous,

audio-sound transmitters.

The main objects of this invention are: to "provide an improved structuring of audio-sound transmitters'for subaqueous use; to provide'animproved'form and arrangement of identically-structured permanent-magnet assemblies juxtaposed in axial opposition to a'diaphragm within an improved-form two-piece housing assembly;

to provide a specially suited material and formedarrangement of the diaphragm between the opposed permanent magnet assemblies; and to provide an improved subaque- .ous audio-sound transmitter of this kind of such simple construction as to make its manufacture and marketing very inexpensive and its use highly effective in varying depths of.water.

In the adaptation shown in the accompanying drawings:

.FIG. 1 is a Water-side face view of an audio-sound transmitter constructed in accordance with this invention;

FIG. 2 is a sectional view of the same taken on the plane of the line 22 of FIG. 1;

FIG. 3 is an opposite face View of the transmitter shown in FIGS. 1 and 2;

FIG. 4 is another sectional view of the transmitter, constructed in accordance with this invention, taken on the plane of the line 440f FIG. 1;

FIG. 5v is a detail, sectional view of the permanent magnet assemblies, forming a part of this invention; and

FIG. 6 is a diagrammatic view of the dominating magnetic lines of flux indicative .of the functioning of this transmitter.

The essential concept of this invention involves a pair .of similarly-structured, voice-coil-activated magnet as- 12 mounted in closely opposed relationship on andwithin a pair of differently-structured, interconnected-housing elements 13 and 14, respectively, with an interposed diaphragm 15.

The magnetassemblies 11 and 12 comprise, respectively, -a magnet ring 16 and17,.on one side of which is adhered the respectiveferrous disks 18 and 19 supported on center stud shafts 21 and 22 and embracing voice coils 23 and 24, respectively.

Each ring magnet is of the permanent type andmade from materials which retain a high residual inductance and is magnetized through its thickness, i.e. .axially. Hence, one face presents the N-pole 'and'the other face 3,231,853 Patented Jan. 25, 1966 presents the S-pole. The disks 18 and 19 are formed of steel or other highly magnetic conducting materials. The disks are of somewhat smaller size than the external diameter as the rings 16 and 1 7 to prevent magnetic shunting over its outer edges; and are bonded in direct and firm contact with one face of the respective rings 16 and 17. Such bonding. may be by a suitable adhesive or by nonmagnetic fasteners, such as screws or rivets. The stud shafts 21 and 22.also' are formed of steel or other highly magnetic conducting materials. These stud shafts 21 and 22 have reduced diameter-threaded shanks 26 and 27. As will be explained presently, these stud shaftsare secured concentrically of and in firm contact with the respective disks 18 and 19.

The housing elements 13 and 14, for-med of non-magnetic materials (aluminum, bronze, stainless. steel, or plastics) are differently structured to fit face-to-face to enclose the two juxtaposed magnet assemblies 11 and 12 with the interposed diaphragm 15. The element 13 is a machine-recessed disk, the details of which will be explained presently. This disk element 13 when assembled with the element 14 provides an air-tight chamber 25 around the magnet assembly 11 and at one side of the diaphragm 15. The element -14 is a machined ring'with .a diametrical bridge 26, the details of which will be explained presently. It provides an open chamber 27 arounduthe magnet assembly 12 and the other side of the diaphragm 15.

The housing element -13 is dish-like in cross-section and circumferentially recessed, inwardly of its outer perimeteryto form an-axially-disposed machined-surface -28 and a right angle, radially-disposed machined-surface 29 directly inward of an annular rim 31. Further in- -wardly the element 13 is recessed to produce an offset radially-disposed machined-surface 32. Still further inwardly on this element 13 is a smaller-diameter recess '33 which forms a pocket for the lead wires 34 from the voice coil 22, as will be explained presently.

The. ring-like housing element 14 is circumferentially recessed directly inward of its perimeter to form an axially-disposed annular rim 35 adapted to telescope into the recess formed by the right-angle surfaces '28 and29. lnwardly of this rim 35 the element 14 is further recessed to provide a radially-disposed, machined surfacev36. The-bridge .26 on this element 14-m0unts "a concentric hub 37 which is recessed at '38 to form a pocket for the lead wires' 39 from the voice coil 24.

In this complete assembly these thusly-structured housing elements 13 and 14 are set in opposed relationship as shown in FIG. 2 and secured together by a series of screw fasteners 41' (FIG. 1). The diaphragm 15 is clamped betweenthe machined surface 29 and to that of the rim '35 with a neoprene gasket 42' (FIG. 2) interposed betweenJthe diaphragm 15 and the machined surface 29.

The thin diaphragrn 15 is formed of steel or other ferric alloys whichhave a relativehigh magnetic resistance to the flux. It is'advantageous to minimize the strength of the magnetic flux in radial direction through the thickness of the-diaphragm, in order to prevent magnetic short circuit of the juxtaposed magnet assemblies.

However, the:magnetic lines of flux, perpendicular to .the thickness of the. diaphragm do not find high magnetic resistance, due to the thin section of the diaphragm. The

magnetic field in perpendicular direction to the plane of the diaphragm becomes intense. This is the same direction the diaphragm moves in excursions caused by voicecoil attenuation.

Therefore it is possible to make the flat and rigid diaphragm responsive to voice coil attenuations with relative small electric energy.

A flat and rigid diaphragm represents a wall in contact with the water. Sound vibrations of the diaphragm act like undamped shock-waves capable of propagating enormous distances in Water.

The stud shafts 21 and 22 are formed of steel or some suitable ferric-powdered composition. The heads 51 and 52 on these stud shafts 21 and 22 mount the respective voice coils 23 and 24, with the shank parts 21' and 22 inserted through the aligned axial bores in the respective housing elements 13 and 14. Nut 44 and cap 48 with an interposed lock washer inwardly of the nut 44 and a watertight gasket inwardly of the cap 48, are threaded onto the respective stud shanks 21' and 22' and turned up against the exterior faces of the housing elements 13 and 14 to draw the shoulders 45 and 46, of the stud-shaft heads 51 and 52, up against the disks 18 and 19 and thereby secure the disks in fluid-tight contact with the machined surfaces 32 and 36 of the respective housing elements 13 and 14. The heads 51 and 52 of the stud shafts 21 and 22 are of an axial length such that in their fixed positions on the housing elements 13 and 14 the gaps between the heads 51 and 52 and the diaphragm 15 are approximately .040.

The stud shaft 21 has a central bore 47 extending throughout its length to provide communication with the chamber 25 established by the diaphragm 15 interposed between the assembled housing elements 13 and 14. The outer end of the shank 21' is fitted with an air-sealing cap 48. Such a cap is in place when the transmitter is to be used in shallow water depths around 30 feet. When the transmitter is to be used in deeper water, the cap 48 is replaced -by a pressure-compensating air-bag (not shown).

The transmitter being thusly completely assembled, the chamber 25 is sealed off from the ambient water when the transmitter is in use. It is imperative that no water whatever be allowed to enter the trapped air in this chamber 25. Trapped air is necessary to furnish the acoustical impedance for the diaphragm. Since the acoustical impedance between water and air is 3000:1 such a small amount of trapped air in the chamber 25 is ample for the effective functioning of such a structured transmitter as herein shown and described.

The chamber 27, in the ring-shaped housing element 14, is open to the ambient water, when the transmitter is in use, through the opening 49 (FIG. 1) defined by the inner wall of the element 14.

As shown in FIG. 2 the leads from the voice coil 23 extend out from the housing element 13 through a coupling 53, screwed into the housing element 13, and into a conduit 54 leading from the coupling to the power-pack, not shown, the location of which is usually carried on the divers suit or belt. The leads 39 from the voice coil 24 are also connected with a cable to the water type powerpack and miter connected with conduit 54 so that both voice coils may be connected in series or parallel, as desired.

A very important factor of the above-described form and arrangement of the magnet assemblies 11 and 12 in the housing elements 13 and 14 has to do with the polarity created by the opposed rings '16 and 17 and the studshaft heads 51 and 52, as shown by the magnetic lines of FIG. 6. As indicated in this FIG. 6, the N-pole face of the ring 16 is in contact with the disk 18 whereas the S- pole face of the ring 17 is in contact with the disk 19. Thus, the S-pole of the ring 16 is opposed to the N-pole of the ring 17. The opposite obtains with the heads 51 and 52. The S-pole of the head 51 is in contact with the disk 18 and the N-pole of the head 52 is in contact with the disk 19. Thus the N-pole of the head 51 is opposed to the S-pole of the head 52. Consequently, an ideal magnetic configuration exists to drive the diaphragm 15. That configuration is diagrammed by the dotted arrow lines of the flux path in FIG. 6, however they have a long path radially through the thickness of the diaphragm. Also as shown in FIG. 6 by the dash-dot lines these represent the shorter axial flux path. Both flux paths contribute to a large percentage the function of this device. The important and desirable result is that the magnetic lines of force, at any point of the magnetic fields, are traversing the diaphragm 15 perpendicular to the plane thereof. This is the same direction as the flexing of the diaphragm 15 will take, caused by signal attenuation of the magnetic fields.

The voice coils 23 and 24, being inserted over the stud shaft 51 and 52, respectively, may be connected in series or parallel, and the signal arrives in both heads 51 and 52 simultaneously. The voice coils 23 and 24 are connected in such a way that if one coil strengthens and adds to its magnetic field the other coil will diminish or subtract from the magnetic field. This allows for one direction flexing of the diaphragm 15. A reverse signal will cause an opposite flexing of the diaphragm 15. Such a structured subaqueous audio-sound transmitter opens up a new field of use. It is capable of pocket size production for underwater communication between divers. For close range operation in turbulent water of any depth, an energy input of 3 watts is sufficient. In shallow quiet water communication can be effective for hundreds of feet. However, With an increase in power to 30 Watts communication can be effected at greater distances without the likelihood of damage to the instrument, provided matching voice coils are used. The water facing voice coil is cooled by direct contact with the water. The inner voice coil is cooled by a lesser degree, by heat transfer to its center stud, with its outer end exposed. to water.

It will be understood that details of the construction shown may be altered or omitted without departing from the spirit of the invention as defined by the following claims.

I claim:

1. A subaqueous audio-sound transmitter comprising, a pair of recessed housing elements secured in axiallyopposed relationship, a diaphragm interposed between the housing elements and forming chambers between the diaphragm and the inner recessed faces of the respective housing elements, one of which chambers is fluid-sealed, a pair of stud shafts fixed on the respective housing elements with the inner ends of the shafts concentrically juxtaposed on opposite sides of the diaphragm, a pair of permanent axially-magnetized annuli bonded to a respective pair of disks and anchored against the inner recessed faces of the respective housing elements, a pair of voice coils embracing the inner ends of the respective studshafts Within the respective annuli, and cables extending outwardly of the respective housing elements for connection of the voice coils to a power pack.

2. A subaqueous audio-sound transmitter as set forth in claim 1 wherein the inner ends of the respective studshafts have heads whereon the respective voice coils are mounted and whereby the disks are anchored in the respective housing elements.

3. A subaqueous audio-sound transmitter as set forth in claim 1 wherein the housing element other than the one having the fluid-sealed chamber is in the form of a ring with an exterior integrated bridge whereon is supported the respective stud shafts.

4. A subaqueous audio-sound transmitter as set forth in claim 3 wherein the opposed portions of the housing elements are internally machined to form telescopicallyinterfitting annular rims with the portions inwardly of the respective rims machined to provide flat surfaces against which the respective disks are anchored by the respective stud shafts.

5. A subaqueous audio-sound transmitter comprising,

(a) a pair of housing elements the opposed faces of which are internally machined to provide telescopically-interfitting rims with the portions inwardly of the respective rims machined to provide radiallydisposed annular flat surfaces and axially-inward radially-disposed fiat circularsurfaces,

('b) a diaphragm interposed between the fiat annular surfaces and forming chambers on opposite sides of the diaphragm and the opposed faces of the respective housing elements,

(c) a pair of stud shafts fixed on the respective housing elements with the inner ends having integrated heads concentrically juxtaposed on opposite sides of the diaphragm,

(d) a pair of permanent axially-magnetized annuli bonded to a respective pair of disks and anchored to the respective radially-disposed fiat circular surfaces of the respective housing elements by the engagement of the stud-shaft heads with the disks,

(e) a pair of coils embracing the heads of the respective stud shafts within the respective annuli, and (f) cables extending outwardly of the respective housing elements for connection of the coils to a power pack.

No references cited.

CHESTER L. JUSTUS, Primary Examiner. 

1. SUBAQUEOUS AUDIO-SOUND TRANSMITTER COMPRISING, A PAIR OF RECESSED HOUSING ELEMENTS SECURED IN AXIALLYOPPOSED RELATIONSHIP, A DIAPHRAGM INTERPOSED BETWEEN THE HOUSING ELEMENTS AND FORMING CHAMBERS BETWEEN THE DIAPHRAGM AND THE INNER RECESSED FACES OF THE RESPECTIVE HOUSING ELEMENTS, ONE OF WHICH CHAMBERS IS FLUID-SEALED A PAIR OF STUD SHAFTS FIXED ON THE RESPECTIVE HOUSING ELEMENTS WITH THE INNER ENDS OF THE SHAFTS CONCENTRICALLY JUXTAPOSED ON OPPOSITE SIDES OF THE DIAPHRAGM, A PAIR OF PERMANENT AXIALLY-MAGNETIZED ANNULI BONDED TO A RESPECTIVE PAIR OF DISKS AND ANCHORED AGAINST THE INNER RECESSED FACES OF THE RESPECTIVE HOUSING ELEMENTS, A PAIR OF VOICE COILS EMBRACING THE INNER ENDS OF THE RESPECTIVE STUDSHAFTS WITHIN THE RESPECTIVE ANNULI AND CABLES EXTENDING OUTWARDLY OF THE RESPECTIVE HOUSING ELEMENTS FOR CONNECTION OF THE VOICE COILS TO A POWER PACK. 